Contractile Filopodia and in Vivo Cell Movement in the Tunic of the Ascidian, Botryllus Schlosseri

1974 ◽  
Vol 15 (3) ◽  
pp. 513-535
Author(s):  
C. S. IZZARD
Keyword(s):  
Cell Body ◽  
Significant Role ◽  
Cell Movement ◽  
Time Lapse ◽  
Botryllus Schlosseri ◽  
Change Direction ◽  
The Matrix

The in vivo movement of one class of cells in the tunic of the ascidian Botryllus schlosseri has been analysed using differential interference optics and time-lapse cinematography. Long (up to 200 µm), thin (0.35-0.5 µm diameter) filopodia radiate from the cell-body into the matrix of the tunic. Movement of the cell-body consists of a series of short, jerky displacements with frequent changes in direction between successive displacements. The net displacement of the cell may be extremely small when the displacements are short and frequently change direction, or considerable when successive displacements show a persistence of direction (up to 114 µm in 60 min). Deformation of the elastic cuticle covering the tunic at points of attachment of the filopodia has been used to record qualitatively changes in tension in the filopodia. Correlation of the changes in tension with changes in length of the filopodia and movement of the cell-body have permitted the following conclusions. Active contractions of filopodia (i.e. increase in tension during shortening) stretch and move the cell-body. These movements exert a force on trailing or opposing filopodia. Relaxations of filopodia (i.e. decrease in tension during lengthening) result in small movements of the cell-body due to the recoil of tension in the cell-body and opposing filopodia. The position of the cell-body in space at any one instant in time is therefore the resultant of the forces developed in all the filopodia. Movement results from unilateral modulation of the tension developed in the filopodia. Active contractions play a more significant role in movement than relaxations.

scholarly journals An In Vitro Model for Assessing Corneal Keratocyte Spreading and Migration on Aligned Fibrillar Collagen

2018 ◽  
Vol 9 (4) ◽  
pp. 54 ◽  
Author(s):  
Pouriska Kivanany ◽  
Kyle Grose ◽  
Nihan Yonet-Tanyeri ◽  
Sujal Manohar ◽  
Yukta Sunkara ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Cell Movement ◽  
Time Lapse ◽  
Collagen Fibrils ◽  
Fibrillar Collagen ◽  
Freeze Injury

Background: Corneal stromal cells (keratocytes) are responsible for developing and maintaining normal corneal structure and transparency, and for repairing the tissue after injury. Corneal keratocytes reside between highly aligned collagen lamellae in vivo. In addition to growth factors and other soluble biochemical factors, feedback from the extracellular matrix (ECM) itself has been shown to modulate corneal keratocyte behavior. Methods: In this study, we fabricate aligned collagen substrates using a microfluidics approach and assess their impact on corneal keratocyte morphology, cytoskeletal organization, and patterning after stimulation with platelet derived growth factor (PDGF) or transforming growth factor beta 1 (TGFβ). We also use time-lapse imaging to visualize the dynamic interactions between cells and fibrillar collagen during wound repopulation following an in vitro freeze injury. Results: Significant co-alignment between keratocytes and aligned collagen fibrils was detected, and the degree of cell/ECM co-alignment further increased in the presence of PDGF or TGFβ. Freeze injury produced an area of cell death without disrupting the collagen. High magnification, time-lapse differential interference contrast (DIC) imaging allowed cell movement and subcellular interactions with the underlying collagen fibrils to be directly visualized. Conclusions: With continued development, this experimental model could be an important tool for accessing how the integration of multiple biophysical and biochemical signals regulate corneal keratocyte differentiation.

scholarly journals Cytoplasmic dynamics of myosin IIA and IIB: spatial ‘sorting’ of isoforms in locomoting cells

1998 ◽  
Vol 111 (15) ◽  
pp. 2085-2095 ◽  
Author(s):  
J. Kolega
Keyword(s):  
Cultured Cells ◽  
Myosin Ii ◽  
Cell Movement ◽  
Leading Edge ◽  
Time Lapse ◽  
Living Cells ◽  
Immunofluorescence Staining ◽  
Spatial Sorting ◽  
Time Lapse Imaging

Different isoforms of non-muscle myosin II have different distributions in vivo, even within individual cells. In order to understand how these different distributions arise, the distribution and dynamics of non-muscle myosins IIA and myosin IIB were examined in cultured cells using immunofluorescence staining and time-lapse imaging of fluorescent analogs. Cultured bovine aortic endothelia contained both myosins IIA and IIB. Both isoforms distributed along stress fibers, in linear or punctate aggregates within lamellipodia, and diffusely around the nucleus. However, the A isoform was preferentially located toward the leading edge of migrating cells when compared with myosin IIB by double immunofluorescence staining. Conversely, the B isoform was enriched in structures at the cells' trailing edges. When fluorescent analogs of the two isoforms were co-injected into living cells, the injected myosins distributed with the same disparate localizations as endogenous myosins IIA and IIB. This indicated that the ability of the myosins to ‘sort’ within the cytoplasm is intrinsic to the proteins themselves, and not a result of localized synthesis or degradation. Furthermore, time-lapse imaging of injected analogs in living cells revealed differences in the rates at which the two isoforms rearranged during cell movement. The A isoform appeared in newly formed structures more rapidly than the B isoform, and was also lost more rapidly when structures disassembled. These observations suggest that the different localizations of myosins IIA and IIB reflect different rates at which the isoforms transit through assembly, movement and disassembly within the cell. The relative proportions of different myosin II isoforms within a particular cell type may determine the lifetimes of various myosin II-based structures in that cell.

scholarly journals Pericytes derived from the retinal microvasculature undergo calcification in vitro

1990 ◽  
Vol 97 (3) ◽  
pp. 449-461 ◽  
Author(s):  
A.M. Schor ◽  
T.D. Allen ◽  
A.E. Canfield ◽  
P. Sloan ◽  
S.L. Schor
Keyword(s):  
Time Lapse ◽  
Matrix Vesicles ◽  
Histochemical Staining ◽  
Nodule Formation ◽  
Retinal Microvasculature ◽  
The Matrix ◽  
Collagen Substratum ◽  
Characteristic Features

Pericytes isolated from the bovine retinal microvasculature retain characteristic features of their in vivo counterparts, such as the presence of glycogen deposits, long filamentous processes, prominent microfilament bundles and the ability to display two distinct and reversible phenotypes. Time-lapse video-microscopy demonstrated that pericytes tend to overlap and aggregate, even in sparse cultures. After reaching confluence, they form multilayered areas that retract away from each other, resulting in the formation of multicellular nodules. These nodules increase in size and cellularity by going through repeated 5- to 6-h cycles of anchoring, spreading, cell proliferation and retraction. Alkaline phosphatase was not detected in pericytes at subconfluent or confluent densities, but this enzyme was expressed in areas of high cell density, such as multilayers and nodules. Pericytes synthesise and deposit an extracellular matrix at all stages of their in vitro development, including nodule formation. The matrix within the nodules contains cross-striated collagen fibres and matrix vesicles. Needle-like crystals of hydroxyapatite appear to be deposited within the matrix, thus leading to massive calcification of the nodule. Calcification, as assessed by electron microscopy, histochemical staining and X-ray microprobe analysis, occurred on plastic and collagen substrate in the absence of disodium-beta-glycerophosphate. The addition of this compound at 5 or 10 mM or the use of a collagen substratum (rather than plastic), brought forward the process of nodule formation and calcification by 3–6 days. Our results suggest that retinal pericytes may differentiate in vitro along the osteogenic pathway.

FURTHER OBSERVATIONS ON AMOEBOID HAEMOCYTES IN BLABERUS GIGANTEUS (L.) (ORTHOPTERA: BLATTIDAE)

1961 ◽  
Vol 39 (5) ◽  
pp. 755-766 ◽  
Author(s):  
J. W. Arnold
Keyword(s):  
Cell Body ◽  
Time Lapse ◽  
Flat Surfaces ◽  
Variable Form ◽  
Form And Function ◽  
Projection Analysis ◽  
Rapid Elongation ◽  
Wing Veins ◽  
And Function

The movements of amoeboid haemocytes in vivo in wing veins of B. giganteus were studied with the aid of time-lapse cinephotomicrography and projection analysis. They are described here in detail and discussed in relation to haemocyte form and function. Haemocyte motion included non-migratory as well as migratory aspects. Non-migratory motion comprised the slow to turbulent cytoplasmic motion and intermittent probing movements of stationary cells. Active migration occurred in the more or less typical amoeboid fashion and also in the more peculiar contractile manner which involved the projection of hyaline, tactile pseudopodia of variable form and often resulted in extreme and relatively rapid elongation of the cell body. Haemocytes were thus able to move on flat surfaces, to extend themselves across spaces, and to force their way into narrow tissue interstices. These activities demonstrate the versatility of the cells and provide a means of accounting for certain of their functions.

scholarly journals Photoreceptor progenitor dynamics in the zebrafish embryo retina and its modulation by primary cilia and N-cadherin

2020 ◽  
Vol 52 ◽  
Author(s):  
Gonzalo Aparicio ◽  
Magela Rodao ◽  
José L. Badano ◽  
Flavio R. Zolessi
Keyword(s):  
Cell Body ◽  
Primary Cilia ◽  
Outer Nuclear Layer ◽  
Time Lapse ◽  
Apical Surface ◽  
Apical Position ◽  
Transgenic Expression ◽  
Basal Process ◽  
Maturation Stages

Photoreceptors of the vertebrate neural retina are originated from the neuroepithelium, and like other neurons, must undergo cell body translocation and polarity transitions to acquire their final functional morphology, which includes features of neuronal and epithelial cells. We analyzed this process in detail on zebrafish embryos using in vivo confocal microscopy and electron microscopy. Photoreceptor progenitors were labeled by the transgenic expression of EGFP under the regulation of the photoreceptor-specific promoter crx, and structures of interest were disrupted using morpholino oligomers to knock-down specific genes. Photoreceptor progenitors detached from the basal retina at pre-mitotic stages, rapidly retracting a short basal process as the cell body translocated apically. They remained at an apical position indefinitely to form the outer nuclear layer (ONL), initially extending and retracting highly dynamic neurite-like processes, tangential to the apical surface. Many photoreceptor progenitors presented a short apical primary cilium. The number and length of these cilia was gradually reduced until nearly disappearing around 60 hpf. Their disruption by knocking-down ift88 and elipsa caused a notorious defect on basal process retraction. To assess the role of cell adhesion in the organization of photoreceptor progenitors, we knocked-down cdh2/N-cadherin and observed the cell behavior by time-lapse microscopy. The ectopic photoreceptor progenitors initially migrated in an apparent random manner, profusely extending cell processes, until they encountered other cells to establish cell rosettes in which they stayed acquiring the photoreceptor-like polarity. Altogether, our observations indicate a complex regulation of photoreceptor progenitor dynamics to form the retinal ONL, previous to the post-mitotic maturation stages.

scholarly journals The onset of whole-body regeneration in Botryllus schlosseri: morphological and molecular characterization

2022 ◽  
Author(s):  
Lorenzo Ricci ◽  
Bastien Salmon ◽  
Caroline Olivier ◽  
Rita Andreoni-Pham ◽  
Ankita Chaurasia ◽  
...  
Keyword(s):  
Time Lapse ◽  
Morphological Characterization ◽  
Whole Body ◽  
Laboratory Model ◽  
Cell Transplant ◽  
Botryllus Schlosseri ◽  
Transcriptomic Response ◽  
Closely Related Species ◽  
Morphological And Molecular Characterization

Colonial tunicates are the only chordates that regularly regenerate a fully functional whole body as part of their asexual life cycle, starting from specific epithelia and/or mesenchymal cells. In addition, in some species, whole-body regeneration (WBR) can also be triggered by extensive injuries, which deplete most of their tissues and organs and leave behind only small fragments of their body. In this manuscript, we characterized the onset of WBR in Botryllus schlosseri, one colonial tunicate long used as a laboratory model. We first analyzed the transcriptomic response to a WBR-triggering injury. Then, through morphological characterization, in vivo observations via time-lapse, vital dyes, and cell transplant assays, we started to reconstruct the dynamics of the cells triggering regeneration, highlighting an interplay between mesenchymal and epithelial cells. The dynamics described here suggest that WBR in B. schlosseri is initiated by extravascular tissue fragments derived from the injured individuals rather than particular populations of blood-borne cells, as has been described in closely related species. The morphological and molecular datasets here reported provide the background for future mechanistic studies of the WBR ontogenesis in B. schlosseri and allow to compare it with other regenerative processes occurring in other tunicate species and possibly independently evolved.

Cell Morphologies and Contacts in Annual Fish Embryos

1980 ◽  
Vol 38 ◽  
pp. 706-707
Author(s):  
Roland Lesseps
Keyword(s):  
Developmental Stages ◽  
Single Cells ◽  
Cell Movement ◽  
Time Lapse ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Electron Microscopic ◽  
Annual Fish ◽  
Fish Embryos

During epiboly and early dispersed stages, the deep blastomeres of annual fish embryos emigrate from the blastodisc to wander as easily visible single cells in the narrow space between the yolk synctial layer (YSL) and the enveloping cell layer (ECL). Subsequently these deep blastomeres reaggregate and eventually form the definitive embryo. We are studying these morphogen-etic cell movements and the controls that may exist upon cell movement in vivo. Time-lapse cinemicrophotography showed three types of cell movement by the deep blastomeres during epiboly through reaggregation stages [1], The present electron microscopic investigation was undertaken to reveal further details of the intercellular contacts during these developmental stages.

scholarly journals Photoreceptor progenitor dynamics in the zebrafish embryo retina and its modulation by primary cilia and N-cadherin

2020 ◽  
Author(s):  
Gonzalo Aparicio ◽  
Magela Rodao ◽  
José L. Badano ◽  
Flavio R. Zolessi
Keyword(s):  
Cell Body ◽  
Primary Cilia ◽  
Outer Nuclear Layer ◽  
Time Lapse ◽  
Apical Surface ◽  
Apical Position ◽  
Transgenic Expression ◽  
Basal Process ◽  
Maturation Stages

AbstractBackgroundPhotoreceptors of the vertebrate neural retina are originated from the neuroepithelium, and like other neurons, must undergo cell body translocation and polarity transitions to acquire their final functional morphology, which includes features of neuronal and epithelial cells.MethodsWe analyzed this process in detail on zebrafish embryos using in vivo confocal microscopy and electron microscopy. Photoreceptor progenitors were labeled by the transgenic expression of EGFP under the regulation of the photoreceptor-specific promoter crx, and genes of interest were knocked-down using morpholino oligomers.ResultsPhotoreceptor progenitors detached from the basal retina at pre-mitotic stages, rapidly retracting a short basal process as the cell body translocated apically. They remained at an apical position indefinitely to form the outer nuclear layer (ONL), initially extending and retracting highly dynamic neurite-like processes, tangential to the apical surface. Many photoreceptor progenitors presented a short apical primary cilium. The number and length of these cilia was gradually reduced until nearly disappearing around 60 hpf. Their disruption by knocking-down IFT88 and Elipsa caused a notorious defect on basal process retraction. Time-lapse analysis of N-cadherin knock-down, a treatment known to cause a severe disruption of the ONL, showed that the ectopic photoreceptor progenitors initially migrated in an apparent random manner, profusely extending cell processes, until they encountered other cells to establish cell rosettes in which they stayed acquiring the photoreceptor-like polarity.ConclusionAltogether, our observations indicate a complex regulation of photoreceptor progenitor dynamics to form the retinal ONL, previous to the post-mitotic maturation stages.

scholarly journals Dual-wavelength fluorescent speckle microscopy reveals coupling of microtubule and actin movements in migrating cells

2002 ◽  
Vol 158 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Wendy C. Salmon ◽  
Michael C. Adams ◽  
Clare M. Waterman-Storer
Keyword(s):  
Cell Body ◽  
Time Lapse ◽  
Lung Epithelial Cells ◽  
Dual Wavelength ◽  
Convergence Zone ◽  
Retrograde Flow ◽  
Filamentous Actin ◽  
Actin Bundles ◽  
Migrating Cells

Interactions between microtubules (MTs) and filamentous actin (f-actin) are involved in directed cell locomotion, but are poorly understood. To test the hypothesis that MTs and f-actin associate with one another and affect each other's organization and dynamics, we performed time-lapse dual-wavelength spinning-disk confocal fluorescent speckle microscopy (FSM) of MTs and f-actin in migrating newt lung epithelial cells. F-actin exhibited four zones of dynamic behavior: rapid retrograde flow in the lamellipodium, slow retrograde flow in the lamellum, anterograde flow in the cell body, and no movement in the convergence zone between the lamellum and cell body. Speckle analysis showed that MTs moved at the same trajectory and velocity as f-actin in the cell body and lamellum, but not in the lamellipodium or convergence zone. MTs grew along f-actin bundles, and quiescent MT ends moved in association with f-actin bundles. These results show that the movement and organization of f-actin has a profound effect on the dynamic organization of MTs in migrating cells, and suggest that MTs and f-actin bind to one another in vivo.

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